Deprecate passing a non-AbstractExpression node to Parser::setParent()

CHANGELOG

@@ -1,5 +1,6 @@
 # 3.24.0 (2026-XX-XX)
 
+ * Deprecate passing a non-`AbstractExpression` node to `Parser::setParent()`
  * Add support for renaming variables in object destructuring (`{name: userName} = user`)
  * Add `html_attr_relaxed` escaping strategy that preserves :, @, [, and ] for front-end framework attribute names
  * Add support for short-circuiting in null-safe operator chains

doc/deprecated.rst

@@ -238,6 +238,10 @@ Parser
 * Passing ``null`` to ``Twig\Parser::setParent()`` is deprecated as of Twig
   3.12.
 
+* Passing a non-``AbstractExpression`` node to ``Twig\Parser::setParent()`` is
+  deprecated as of Twig 3.24; the method will require an ``AbstractExpression``
+  instance in Twig 4.0.
+
 * The ``Twig\Parser::getExpressionParser()`` method is deprecated as of Twig
   3.21, use ``Twig\Parser::parseExpression()`` instead.
 

src/Parser.php

@@ -416,6 +416,10 @@ class Parser
             trigger_deprecation('twig/twig', '3.12', 'Passing "null" to "%s()" is deprecated.', __METHOD__);
         }
 
+        if (null !== $parent && !$parent instanceof AbstractExpression) {
+            trigger_deprecation('twig/twig', '3.24', 'Passing a "%s" instance to "%s()" is deprecated, pass an "AbstractExpression" instance instead.', $parent::class, __METHOD__);
+        }
+
         if (null !== $this->parent) {
             throw new SyntaxError('Multiple extends tags are forbidden.', $parent->getTemplateLine(), $parent->getSourceContext());
         }

tests/ParserTest.php

@@ -26,6 +26,7 @@ use Twig\Error\SyntaxError;
 use Twig\Lexer;
 use Twig\Loader\ArrayLoader;
 use Twig\Node\EmptyNode;
+use Twig\Node\Expression\ConstantExpression;
 use Twig\Node\Node;
 use Twig\Node\Nodes;
 use Twig\Node\SetNode;
@@ -208,7 +209,7 @@ EOF, 'index')));
     protected function getParser()
     {
         $parser = new Parser(new Environment(new ArrayLoader()));
-        $parser->setParent(new EmptyNode());
+        $parser->setParent(new ConstantExpression('base.html', 1));
 
         $p = new \ReflectionProperty($parser, 'stream');
         $p->setValue($parser, new TokenStream([], new Source('', '')));